1. Field of the Invention
The present invention relates to microencapsulated 1,2-benzazoles and their use in the treatment of warm blooded animals suffering from mental illness. More particularly, the present invention relates to microencapsulated 3-piperidinyl-substituted 1,2-benzisoxazoles and 1,2-benzisothiazoles and their use in the treatment of mental patients.
2. Description of the Related Art
Strupczewski et al., in U.S. Pat. No. 4,352,811 and U.S. Pat. No. 4,458,076, describe 3-piperidinyl-1,2-benzisoxazoles and 3-piperidinyl-1,2-benzisothiazoles having antipsychotic and analgesic properties.
Kennis et al., U.S. Pat. No. 4,804,663, disclose 3-piperidinyl-1,2-benzisothiazoles and 3-piperidinyl-1,2-benzisoxazoles and their pharmaceutically acceptable acid addition salts that have antipsychotic properties and are useful in the treatment of a variety of complaints in which serotonin release is of predominant importance. In particular, 3-[2-[4-(6-fluoro-1,2-benzisoxazol-3yl)-1-piperidinyl)ethyl]-6,7,8,9-tetrahydro-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one (“Risperidone”) is disclosed.
Janssen et al., U.S. Pat. No. 5,158,952, 3-piperidinyl-1,2-benzisoxazoles having long-acting antipsychotic properties and which are useful in the treatment of warm-blooded animals suffering from psychotic diseases. In particular, 3-[2-[4-(6-fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl)ethyl]-6,7,8,9-tetrahydro-9-hydroxy-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one (“9-hydroxy-Risperidone”) is disclosed.
A number of methods are known by which compounds can be encapsulated in the form of microparticles. In many of these processes, the material to be encapsulated is dispersed in a solvent containing a wall forming material. At a single stage of the process, solvent is removed from the microparticles and thereafter the microparticle product is obtained.
An example of a conventional microencapsulation process and microparticles produced thereby is disclosed in U.S. Pat. No. 3,737,337, incorporated by reference herein, wherein a solution of a wall or shell forming polymeric material in a solvent is prepared. The solvent is only partially miscible in water. A solid or core material is dissolved or dispersed in the polymer-containing solution and, thereafter, the core-material-containing solution is dispersed in an aqueous liquid that is immiscible in the organic solvent in order to remove solvent from the microparticles.
Another example of a process in which solvent is removed from microparticles containing a substance is disclosed in U.S. Pat. No. 3,523,906. In this process a material to be encapsulated is emulsified in a solution of a polymeric material in a solvent that is immiscible in water and then the emulsion is emulsified in an aqueous solution containing a hydrophilic colloid. Solvent removal from the microparticles is then accomplished by evaporation and the product is obtained.
In still another process as shown in U.S. Pat. No. 3,691,090 organic solvent is evaporated from a dispersion of microparticles in an aqueous medium, preferably under reduced pressure.
Similarly, the disclosure of U.S. Pat. No. 3,891,570 shows a method in which solvent from a dispersion of microparticles in a polyhydric alcohol medium is evaporated from the microparticles by the application of heat or by subjecting the microparticles to reduced pressure.
Another example of a solvent removal process is shown in U.S. Pat. No. 3,960,757.
Tice et al., in U.S. Pat. No. 4,389,330, describe the preparation of microparticles containing an active agent—which may, inter alia, be a psychotherapeutic agent—by a method comprising: (a) dissolving or dispersing an active agent in a solvent and dissolving a wall forming material in that solvent; (b) dispersing the solvent containing the active agent and wall forming material in a continuous-phase processing medium; (c) evaporating a portion of the solvent from the dispersion of step (b), thereby forming microparticles containing the active agent in the suspension; and (d) exacting the remainder of the solvent from the microparticles.
Tice et al., in U.S. Pat. No. 4,530,840, describe the preparation of microparticles containing an anti-inflammatory active agent by a method comprising: (a) dissolving or dispersing an anti-inflammatory agent in a solvent and dissolving a biocompatible and biodegradable wall forming material in that solvent; (b) dispersing the solvent containing the anti-inflammatory agent and wall forming material in a continuous-phase processing medium; (c) evaporating a portion of the solvent from the dispersion of step (b), thereby forming microparticles containing the anti-inflammatory agent in the suspension: and (d) extracting the remainder of the solvent from the microparticles.